Friction brake for vehicles



Aug. 15, 1950 A. Y. DODGE FRIcTIoN BRAKE FORY VEHICLES 2 Sheets-Sheet 1 filed Dec. 29, 1945 Aug. 15, 1950 A. Y. DODGE 2,518,761

FRIc'rIoN BRAKE FOR vEmcLEs Filed Dec. 29, 1945 2 sheets-sheet 2 mmm Patented Aug. 15, 1950 PATENT OIfF-IfCfEgA4 l V2,518,761 A "M 'Farc'rroN BRAKE Fon VEHICLES r Adiel Y.=Dodge,1Rocliford,Ill. 1 n Application December 29, '1945, 'Serial o. 638,166

invention .relates tolbrakesand moreparticularly to 'brakes'of the type adapted tokbe used -onY automotivevehicles' for heavy duty service. The-most commonly used brakes `for heavy Vduty :automotive -servlice 'have Ibeen expanding two vshoe brakesfone-shoe of which has self -actuating characteristics and the other of -whichhas deactuating characteristics. Such 'brakes have :a Vnumber of disadvantages among which are that-.they .caninot employ Vmore than about `22.0 circumferential degrees of' lining, do not Wear the "lining to :good advantage, .tend to :deflect the brake drum out of round during iheavy applications, and impose-.an unbalancing load onthe wheel 'bearings during applications.- `It .is one ofthe obiectsfof the .pres- V.ent invention `to provide a .brake of Y the type adapted for heavy lduty automotive service in 'which -all of these disadvantages Aof `the conventional two shoebrake'are avoided.

It is another .object of'ithe invention vto provide abrake which makes possible the use of a lmaximumcircumferential extentl ofbrakelining, which provides highly desirable wearingcharacteristics, which produces uniform expansion stresses in =the brakedrum to minimize Vdrum deflection, and which` balances radial loads Y.against "ther drum so 4:as not to Iimpose additional bearing-*loads on the wheelbearings Still another object is to provide a brake vwhich is mildly self-actuating in =both directions of rotation.'

A further object lis to provide abra-ke Lwhich lcan `be adjusted vsimply'amj quickly to compensate -orlining-wear. Y 'Astill furtherobject is `to provide a'brake which can be easily and quickly assembled and disas- :sembled either -for original assembly purposes or for repair orreplacement-in thee'ld.

A still further object is to provide abrake controlled 'by ya 4cam in which the followers engaging the cam lie at Idifferent angles to neutralize the jifrictional eiects 'between the cam and the followers. i .Y

' IThe above and other objects and advantages of the invention will be more readily apparent from ithe :following description when read in connection withi fthe accompanying drawing, in

' Fig-ure' l `is an axial sectional view through a Vbrake embodying the invention showing the Ibrake drum in elevation; e Y

Figure 2 is an enlarged partial section Von 'the llni--'o'f Figure l; 1 i

lFigure :3 assection on the 1ine'3-3 .of Jliigure Y TV. J. l. f" .5 Y

'Figure a4 is a partial vsectional Iview illustrating a y:modified construction .of the adiusting means;-

The 'brake of the present 'inventionis adapted to be used with the usual cylinder brake flll :which Amay be :attac-hed te va vehicle wheel :in any' desired manner to provide San inner .cylindrical drum surface. 'Thebrakecomprises asup- Vport which 'is preferably channel 'or 1C :shaped 'in ysection as shown at :Il and which iszxedly mounted 'in anyl desired mannerwithin the drum a' three shoe construction might be .employed :in

which case one -of :the abutments `I3 and the fcorresponding shoe and lever parts would :be omit- Vted. Between the several abutmentsibra'ke shoes are 'mounted which may be lidenticaland which are preferably :of rigid channel shaped .sections as shown at 4:5. 'The brake .shoesectionsemaybe .of maximum depth 'in their center portions'ta- '.pering toward their vends as illustrated yin- Figure "l and :carry linings I6 on their outer surfaces to engage the `innerfdrum surface;l At `their-ends n 'Thefshoes are actuated by jity lo'f actuating levers 'lying rradially within-the shoes.

the brake shoes A'carry .abutment platesrI'I-Which are v.adapted to engage-the .abutments lying'fadjacent their opposite ends :as .shown in vFigure 1. The shoes are preferably urged inward :toward Aengagement with the -abutments and Vaway from 'the drum by means of 'individual coilsprings4 18 connected to pins |9 on the support "H :and to flanges onv the shoes adjacent" the cor-ners 'of 'the shoes. In this wayeach shoe is individually urged inward-and away from the drum `Sby four separate springs connected -to the shoes adjacent its four v'extreme corners so thatfthe shoes tend to move uniformly away from the .drum withoutftilting means of a plural- Asshown, there are four 4such levers,2fl, y22, 23 and r2li, which register respectively with the Y several -shoes vl 5. Theflevers mayccnveniently 'bie for-med :of channel section as vbest seen .in-.Figure -3 and may be of such a size as to lie between lthe sides of the channel shaped brake shoes;l The adjacent ends ofthe levers 2| and 22 are connected 'by a floating pivot 25 .and the adjacent tends of -the levers .23 and 24 are similarly. connected 'by a iloating pivot .26.*V 4'l'headjacent en'dsvof levers Jcairr and follower plate.

22 and 23 are connected by a pivot 21 carried by a mounting plate 28 which is mounted on the support by means of bolts or the like extending through slots 23 in the plate so that the plate can move circumferentially to adjust the position of the pin 21. When the pin 21 is adjusted to the proper circumferential position, the plate 28 may be secured in that position by tightening its mounting bolts so that the pin 21 then becomes aiixed pivot point. Y Y

The levers are adapted to be spread by any desired means, either pneumatic, hydraulic, magnetic or mechanical, acting on the adjacent ends of the levers 2| and 24 to separate them. As shown the levers are controlled by a rotatable cam 3| which is rotatably mounted on the sup port between the adjacent ends of the levers 2| and 24. The cam as shown has opposite cam surfaces which are shaped according to a substantially constantly rising spiral to provide univform operating characteristics throughout the range of operation. One side of the cam engages 'a camfollower plate 32 on the end of the lever 2I= and whose surface lies substantially parallel to a radius through the cam axis. The lever 24 carries a cam follower plate 33 which lies at an angle to the radius through the cam axis equal lo-substantially twice the angle whose tangent is-equal to the coefficient of friction between the With this construction the outward forces on the ends of levers 2| and `24 upon rotation of the cam due to wiping fric- 'tion'of the cam over the plates 32 and 34 are substantially equalized since the frictional effect on the cam followers is neutralized. The levers are urged inward to bring the follower plates into 'engagement with the cam by return springs 34 lying within the channel shaped levers and engaging the ends of the levers 2| and 24 and fixed spring brackets 35 on the support.

To connect the levers with the respective shoes,l pivotally mounted struts 36 are provided which are' pivotally connected to vthe levers by pins 31. The stnuts 36 terminate at their outer ends in substantially ball shaped portions 38, as best seen in Figure 3, which fit slidably into complementary sockets formed in the centralY portions of the shoes. With this construction, when the cam is turned to spread the ends of the levers 2| and 24, the levers'will expand and through the struts 36 will force the shoes outward into` engagement with the drum. Assuming a counter-clockwise rotation of the drum, as seen in Figure 1, the shoes will abut against the abutment I2, I3 or I4 which is counter-clockwise with respectvto each shoe so that the abutments provide fixed stops for the shoes. The abutment plates II at the ends of the shoes are preferably substantially parallel to a radius through the center of the adjacent abutment so that pressure of the shoe -move the shoes inward until they engage the abutments at their opposite ends.

In initially adjusting the brake for proper application, the'bolts holding the mounting plate may be loosened and the cam 3| may be turned Ytoapply the brake. At this time .the mounting "can be lifted from the assembly for urelining or replacement. If desired, pins 39- may be provided on the levers to limit swinging movement of the struts 36 when the shoes are removed so vthat these struts will not swing too far out of position to make it difcult to replace the shoes.

In order to adjust the brake to compensate for lining wear, the abutments I3 and I4 are preferably made adjustable. As explained these abutments are rotatably mounted on the support II while the abutment I2 may be xed, since no adjustment at this point is necessary. As shown, the abutment I4 is formed with symmetrical spiral curves on its opposite sides, the curves preferably being made up of a series of connected flats to increase the bearing area between the abutment and the ends of the 4adjacent shoes. When the abutment I4 is turned to the position shown in Figure 1, its circumferential width is at a minimum, and maximum inward movement of the shoes is permitted. When the abutment is turned counter-clockwise, its Yeffective width increases to move the shoes out so that increased clearance between the worn linings on vthe shoes and the drum will be taken up.

The abutments I3 are formed with a single spiral surface and an arcuate surface opposite thereto. As shown, the spiral surfaces are made up of a series of connected flats 42 andthe arcuate surfaces are similarly made up of a series of connected ilats 43 to increase the bearing area. When these abutments are turned counterclockwise, as seen in Figure l, they will tend to move the shoes lying between them and the fixed abutment I2 outwardly due to the effect of the spiral surfaces. Since the arcuate 4surfaces of these abutments engage the ends of the shoes between them and the abutment I4, these latter shoes will not be affected by turning of the abutments I3. It will be noted that inall cases the adjustment of the shoes produced by turning of the adjustable abutments causes a movement of the shoes in the same direction as the expanding movement of the levers. This maintains the same effective relationship between the'several shoes and their respective levers Yin all positions of adjustment.

If desired, the abutments I3 may be made, as shown in Figure 4, with one arcuate curved surface 44 and an opposite spiral surface made up of a series of connected flats 45, In this connection,l if the abutment is turned, the arcuately curved surface 44 will produce no movement of the adjacent shoe, but the spiral surface 45 will move the shoe adjacent thereto outwardly toward the drum.

While one embodiment of the invention has -been shown and described in detail, it will be understood that this is illustrative only and is not to be taken as a definition of the scope of the invention, reference being had for this purpose to the appended claims.

What is claimed is: '1

1. A brake comprising a series of xed 'abutvments at least three in number, a series of shoes equal in number to the abutments lying .in annular array between the abutments with their ends adapted to engage adjacent abutments, a plurality of pivotally interconnected levers lying radially within the shoes, the levers being equal in number to the shoes and registering respectively with the shoes, means to separate the ends of two adjacent levers to expand the series of levers radially, means providing a xed mounting for the pivotal connection between levers which is diametrically opposite the separating means, and a strut pivotally engaging each lever and the center of its corresponding shoe.

2. A brake comprising a support, a plurality of abutments carried by the support for rotary adjustment about Xed axes, a plurality of shoes equal in number to the abutments lying in annular array between the abutments with their ends adapted to engage adjacent abutments, a plurality of pivotally connected levers lying radially within the shoes, means to separate the ends of a pair of adjacent levers to expand the levers outward, said means being in radial alignment with one of the abutments, and struts pivotally connecting the levers to the shoes to move the shoes outward as the levers expand, said one of the abutments being adjustable te move both adjacent shoes, the diametrically opposite abutment being fixed, and the intermediate abutments being adjustable to move only the shoe on the side thereof adjacent the fixed abutment.

3. A brake comprising a support, a plurality of abutments carried by the support for rotary adjustment about xed axes, a plurality of shoes equal in number to the abutments lying in annular array between the abutments with their ends adapted to engage adjacent abutments, a plurality of pivotally connected levers lying radially within the shoes, means to separate the ends of a pair of adjacent levers to expand the levers outward, said means being in radial alignment with one of the abutments, and struts pivotally connecting the levers to the shoes to move the shoes outward as the levers expand, said one of the abutments having on both sides successively effective flat surfaces at progressively increasing distances from its center, the opposite abutment being fixed, and the intermediate abutments having spirally arranged fiat surfaces only on the sides thereof adjacent the fixed abutment.

4. A brake comprising a support, four xed abutments carried by the support, four shoes mounted in annular array between the abutments with their ends adapted to engage adjacent abutments, four pivotally connected levers lying radially within and registering with the shoes, a mounting plate carrying one of the piv ots for the levers, means connecting the mounting plate to the support for circumferential adjustment thereon, means diametrically opposite the mounting plate to spread the ends of the adjacent pair of levers, and struts pivotally connected to the shoes and levers to move the shoes outward as the levers are expanded.

5. In a brake, a pair of actuating members adapted to be spread to apply the brake, a cam lying between the ends of the actuating members to spread them, the cam having opposite cam surfaces following a substantially constantly rising spiral, a cam follower plate on one of the levers parallel to a radius through the cam axis, and a follower plate on the other member lying at an acute angle to said radius equal to substantially twice the angle whose tangent equals the coefficient of friction between the cam and plate.

6. In a brake having a support and a plurality of shoes carried on the support for radial movement thereon, operating means comprising a plurality 'of levers at least three in number and corresponding in number to the shoes pivotally interconnected in series with the adjacent ends of two of the levers free, means carried by the central parts of the levers to connect them to the central parts of the shoes respectively, and actuating means to spread the free ends of said two of the levers to expand the levers radially.

7. In a brake having a support and four shoes carried on the support for radial movement thereon, operating means comprising four levers pivotally interconnected end to end with the adjacent ends of two of the levers free, means to connect the pivotal connection opposite the free ends to the support, means to connect the central parts of the levers to the shoes respectively, and actuating means to spread the free ends of said two of the levers radially.

8. A brake comprising an annular channel section support opening radially outward and adapted to fit in a cylindrical brake drum, a plurality of brake shoes movably mounted in annular array in the channel support for radial movement into contact with the drum, abutments for the shoes extending across the channel section of the support and carried by the sides thereof, and a plurality of pivotally interconnected operating levers pivotally mounted in the channel support radially within the shoes.

9. A brake comprising an annular channel section support opening radially outward and adapted to t in a cylindrical brake drum, a plurality of brake shoes movably mounted in the channel support for radial movement into contact with the drum, the shoes being of channel section opening inward, and a plurality of pivotally interconnected operating levers carried in the channel support and lying partially within the channel section of the shoes.

ADIEL Y. DODGE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,663,147 Spotz Mar. 20, 1928 1,937,691 Girling Dec. 5, 1933 2,032,837 Crockett Mar. 3, 1936 

